The present invention relates to miniature push-in lamps for use in a holder, and more particularly to a miniature push-in lamp designed to preclude relative rotation of the bulb and the base, thereby to prevent breakage or displacement the dumet leads.
Miniature lamps are used for the decoration of Christmas trees, commercial displays and the like and, depending upon their size, are known by a variety of different names related to their size. The miniature push-in lamp is an assembly composed of a miniature push-in bulb and a longitudinally extending base. The base includes a body defining an outer surface and an open-top cavity configured and dimensioned to receive a bottom portion of the bulb therein. The bottom of the miniature push-in lamp is configured and dimensioned to be received in a holder therefor so as to provide both electrical communication between the bulb and a power supply associated with the holder and a secure but releasable physical attachment of the lamp and the holder. The base is typically formed of an electrically insulative plastic with the cavity thereof being configured and dimensioned to receive the bulb portion with a push-in (non-rotational) insertion motion. In order to facilitate insertion of the bulb portion into the base cavity, the body typically does not apply to the bulb sufficient frictional forces to preclude relative rotation of the bulb and the body.
In order to provide an electrical connection between the bulb and the holder, dumet leads are provided. These dumet leads are uninsulated thin, flexible wires having one end physically secured to and in electrical communication with the electrical circuitry or filament of the bulb, a main body extending from the bulb portion in the cavity through the body of the base, and the other end disposed on the body outer surface for electrical communication with the electrical contacts of the holder when the lamp is inserted into the holder. Typically, the bottom portion of the body of the base is somewhat wedged shaped with one end of each dumet lead being disposed on a respective one of the small flat outer side surfaces thereof, the base being inserted into the holder with a push-in (non-rotational) insertion motion.
The conventional miniature lamps have not been entirely satisfactory in use. Because the bulb is capable of at least limited rotation relative to the base either during the process of inserting the lamp into the holder or during use of the lamp, the bulb and base may undergo a degree of relative rotation which results in breakage of one or both dumet leads, dumet lead separation from the bulb, and/or repositioning of the dumet lead on the base outer surface such that it is no longer properly positioned for contact with the holder contact. To overcome this problem, a portion of the base body underneath the base outer surface has been cut away so that the remaining strip of the base outer surface (overlying the cut-out portion) can be caused to flex inwardly by the holder when the lamp is inserted into the holder. The locking strip is capable of flexing or bowing inwardly sufficiently to frictionally engage the bulb, thereby to preclude relative rotation of the bulb and the base body.
In order to be effective, however, the lamp must be inserted into the holder to a predetermined depth to assure both appropriate electrical communication (between the dumet leads and the holder contacts) and appropriate physical security (so that the lamp does not fall out of the holder). However, the locking strip provides such a strong resistance to bowing or deflection inwardly that the consumer often fails to insert the base of the lamp to the necessary depth within the cavity of the holder. Presumably, the severe resistance to insertion (i.e., the inward bowing of the strip) is interpreted by the consumer as an indication that the lamp has already reached the limit of its insertability. Thus, while such a lamp upon appropriate insertion into the holder may limit relative rotation between the holder and the base body (and thereby avoid breakage of the dumet leads, their separation from the bulb, and/or their repositioning on the base outer surface), an appropriate full insertion is often not achieved. As a result, either the lamp is likely to become dislodged from the holder or relative rotation between the bulb and the base remains possible.
Furthermore, while the locking strip operates satisfactorily on an appropriately sized bulb to preclude relative rotation between the bulb and the base, there is frequently a substantial variation in the diameter of the commercially available bulbs which range from 4.5-5.5 millimeters in thickness. Strips which are designed to preclude relative rotation of bulbs in the higher diameter range may not effectively preclude relative rotation of bulbs having a diameter in the lower range.
Accordingly, it is the object of the present invention to provide a miniature lamp for use in a holder wherein relative rotation of the bulb and the base body is; precluded when the base is within a holder.
Another object is to provide such a lamp where the base can accommodate minor variations in bulb diameter and still preclude such relative rotation of the bulb and the base body when the base is within a holder.
A further object is to provide such a lamp which is easily insertable into the holder to the desired depth.
It is an object of the present invention to provide in combination such a lamp and a holder therefor.
It is another object to provide such a combination including a releasable locking mechanism for securing the lamp base and holder together.
It is a further object to provide a set or string of lights formed of such combinations.
It is a final object to provide such a lamp and combination which are easy and inexpensive to manufacture, use and maintain.